The present invention relates to the field of ophthalmic surgery, and more particularly to intraocular surgery, and finds special importance in the treatment of lens disorders, such as cataracts, which treatment utilizes phacoemulsification and artifical lens implantation techniques.
Vision, in vertebrate systems, is dependent upon the eye forming an image of an object and sending that image to the sensory centers of the brain. In this process, light rays from an object pass through the cornea, the aqueous humor, the pupil, the intraocular lens and the vitreous humor of the eye. These rays finally reach the retina where they stimulate the optic nerve cells. In turn, the optic nerve carries messages from the nerve cells to the visual cortex of the brain. In essence, the disc-shaped intraocular lens of the eye performs the same function as the lens of a camera, being responsible for focusing incoming light rays onto the retina, the image registering portion of the eye.
The lens of the eye is subject to damage by physical or other external trauma, whether accidental or otherwise, and also by the formation of cataracts. Such damage can affect the ability of the lens to perform its function of focusing and transmitting light rays.
The formation of cataracts are a common disorder of the eye, and are one of the leading causes of blindness in the United States. A cataract is a physical change in the lens characterized by a transformation of the normally transparent lens to a cloudy or opaque state. As a consequence, adequate light cannot reach the associated retina, and vision becomes increasingly blurred. There are several basic types of cataracts, including congenital cataracts, cataracts caused by accidental injury, cataracts caused by disease such as diabetes or glaucoma, and so-called senile cataracts which commonly appear in persons over about 65 or 70 years of age.
Cataracts and other deficiencies of the lenses are generally treated by surgical procedures in which the damaged lens is removed. While removal of the clouded lens will restore light perception, full rehabilitation requires that the refractive power of the natural lens be supplied through some other means.
In the past, the biological lens was simply replaced by glasses and/or contact lenses. However, there were a number of disadvantages and limitations associated with these rehabilitative measures. For example, the magnitude of the optical compensation required to replace a natural lens necessitated very strong lenses, resulting in glasses which were both clumsy and heavy, or contact lenses which were frequently incapable of providing the high focusing strength needed. Moreover, spectacles produced major optical distortions, and some patients, particularly older patients, have found it difficult to adjust to the wear and maintenance of contact lenses.
However, in recent years, advances have led to the development of artificial lenses that are able to replace the damaged natural lens. The availability of artificial intraocular lens implants serves to eliminate or at least minimize the need for contact lenses and eyeglasses following surgery. The artificial lenses can be permanently implanted and serve to mimic the function of the original, natural lens. They are convenient, comfortable and are capable of providing the desired optic strength without distortion.
A number of procedures for removing the damaged lens and replacing it with an artificial lens are known. The most frequently employed and favorably regarded methodology is the extracapsular technique wherein a transverse incision is made in the limbus zone directly through the cornea into the anterior chamber. An artificial replacement lens is then carefully inserted into the eye through the same corneal aperture and manipulated by the surgeon into the position previously occupied by the removed natural lens. One of the major advantages of this technique is that a small incision of only about 3 mm is required to remove the natural lens from the eye and insert an artificial lens. There are, however, a number of significant disadvantages associated with the use of this procedure. Specifically, the transverse incision requires the use of a number of sutures, resulting in additional discomfort and irritation during the healing process. Moreover, a significant amount of undesirable drag on the incisional edges during instrument insertion has been evident. Furthermore, induced astigmatism has been observed in patients treated using this procedure.
New and/or better surgical procedures are needed. The present invention is directed to this important end.
Specifically, it is an object of the present invention to provide a surgical procedure that minimizes trauma to the patient's eye during surgery. A further object is to provide a surgical process that affords the patient a relatively comfortable convalescence following eye surgery. An additional object of the invention is to provide an opthamological technique that minimizes the potential for induced astigmatism. An even further object of the invention is to provide a surgical methodology for the eye that requires less incisional sutures. A still further object is to provide procedure for eye surgery which employs an incision of a sufficient size to enable the use of phacoemulsification techniques and the introduction of an intraocular implant. It is a further object of the invention to provide a surgical process for the eye that results in an incision that experiences minimal drag on its edges during the course of the surgery.